Around here you can get shitty coke for $40 a gram or good quality for about $70. As always it's better to buy bigger, $180-200 an 8th. Coke is only worth it if it is higher quality. Cheap coke is usually very little cocaine, amphetamines, lidocaine and a bunch of other shit. The high it produces tends to feel dirtier.
In my experience good coke comes as pressed rock (doesn't mean it is crack) and will shimmer like an angel in direct light. Cocaine is hygroscopic, it absorbs water from the air and this will cause it to clump up.